I don’t remember where I first ran across the idea, but it's a great way to normalize your view of the image your working on. Photos look markedly different on white, gray and black backgrounds, and the surrounding background can really warp your ability to judge brightness, contrast and even color saturation. My solution is to switch my view between all three backgrounds and tinker with the photo until it looks good all three ways.

Both Lightroom and Photoshop give you the ability to change the background color. Both let you right-click on the background and select a new color. But there's also a trick in Photoshop that lets you quickly cycle between gray, white and black with a simple keystroke. Watch the short video tutorial to see the details.